Conventionally, the change of position of a locking member of a connector assembly is used to detect whether a connector housing is in a half-fitted state. In one, a example connector housing is provided with a see-saw like locking member the anterior end of which is provided with a hook. From a corresponding connector housing projects a stopping member which engages the hook. When the housings are being fitted, the hook rises over the stopping member and the locking member is pushed in with its centre serving as a fulcrum. When the housings are in a correctly fitted state, the locking member reverts to its original position and the hook is engaged by the stopping member and is thereby latched. A detecting member is provided, which is inserted into the lower face of the posterior end of the locking member. If the housings are in a correct fitted state, the locking member returns to its original position and the lower face of the posterior end thereof is open, allowing the insertion of a detecting member. If the housings are stopped in a half-fitted state, the hook has risen onto the stopping member and the locking member has been moved into a position in which its posterior end is down. As a result, the detecting member strikes against the locking member and cannot be inserted, thereby allowing the detection of a half-fitted state.
However, the conventional example has the following problem. In the case where the locking member is of a seesaw type, when the hook on the anterior end has risen onto the stopping member, its other, posterior, end should be down. However, as the locking member is made from resilient plastics material, it is possible that, depending on various circumstances such as the shape of the locking member, only the anterior end bends when the hook has risen up, and the posterior end does not change shape and move down, or only changes shape very slightly. In this case, the detecting member can be inserted into the lower face of the posterior end of the locking member even though the housings remain in a half-fitted state, and the half-fitted state cannot be detected. Consequently, lack of reliability is a problem. The present invention has been developed after taking the above problem into consideration, and aims to present a detecting means which can detect a half-fitted state with a high degree of reliability.